The city of Canberra has adopted a third sister with the signing of a memorandum of understanding between the ACT Government and Wellington council.

The regions' business chambers also formalised an agreement overnight to bolster trade ahead of the launch of direct, three-hour Singapore Airlines flights in September.

The Chief Minister, Andrew Barr, was in the New Zealand capital to promote the ACT and promised to host "Canberra week" later this year to "showcase" the city to Wellingtons.

He met Wellington's mayor, Celia Wade-Brown, who told 666 ABC Canberra the cities had a lot in common.

"We have the most highly educated populations of our countries. And also the highest average income. Both [are] socially progressive cities," she said.

"I think we'll feel reasonably at home in each other's cities but there are a huge number of differences."

"We've probably got more craft beer," Councillor Wade-Brown joked.

The Canberra Business Chamber said the agreement was more than a symbolic relationship.

"We will share information in order to increase local understanding of each other's markets and make sure this filters down to companies so they can make the most of opportunities," CEO Robyn Hendry said.

Canberra also has sister city agreement with Nara in Japan and China's capital Beijing.